Hi,
It's possible but more complex.
You need to customize the file product / listing_add_to_cart_ajax and the file product / quantity.php which display the add to cart button on the listings and on the product page.
There, you have this code for the text of the add to cart button:
$content = JText::_('ADD_TO_CART');
So just after that line, you can add something like that:
$cartClass = hikashop_get('class.cart');
$cart = $cartClass->getFullCart();
if(!empty($cart->products)) {
foreach($cart->products as $p) {
if($p->product_code == $this->row->product_code) {
$content .= ' added';
}
}
}